Blood oxygenator



Julyzs, 1964 J. w. LOVE.

, BLOOD OXYGENATORII.

Filed May 31, 1962 linen r01? flm M Mm irrakme vs,

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United States Patent 3,142,296 BLUGD OXYGENATOR Jack W. Love, 38 FacultyLane, University City, Mo. Filed May 31, 1962, Ser. No. 198,815 6(Iiaims. (Cl. 128-214) This invention relates to extracorporeal bloodoxygena .tion.

The subject of apparatus and methods for oxygenating blood has been wellsummarized in a two-part article entitled Theme and Variations on BloodOxygenators which appeared in Surgery in December 1961 (vol. 50, No. 6,pages 931 et seq.), and February 1962 (vol. 51, No. 2, pages 251 etseq.).

In some of the prior art devices illustrated in this article, domedvessels have been used for various purposes, positive displacement pumpsare shown, and though the use of the arrangement is not indicated, thepiping is such as to permit shunting of the blood (cf. 50:6, page 932,Jacobi, FIG. 4, page 935, Issekutz, FIG. 9, page 936, Euler and Heymans,FIG. but these devices were characterized by complication, theproduction of froth, or considerable violence to the blood.

One of the objects of this invention is to provide apparatus and method,for oxygenating blood, which are simple, safe, inexpensive, gentle andeffective.

Another object is to provide such apparatus which requires so littlepriming as to permit the use of saline solution rather than blood toprime.

Other objects will become apparent to those skilled in the art in thelight of the following description and accompanying drawing.

In accordance with this invention, generally stated, oxygen-poor(venous) blood is oxygenated by filming it gently on the underside of adome of a container which is swept by oxygen-rich gas. Preferably, apart of the oxygenated (arterial) blood is recirculated with additionalvenous blood, through the oxygenating container. The carbon dioxidereleased in the container from the venous blood is swept out with excessoxygen-rich gas. The system is closed, which makes for sterility, andthe gentle filming, along with the construction of the closed system,substantially eliminates frothing of the blood, minimizes the danger ofembolism, and produces relatively little damage to the elements of theblood as compared with the apparatus and method of Euler and Heymans,supra, or Hooker (Surgery 51:2, page 252, FIG. 3), for example.

The construction of the apparatus and simplicity of the method make itpossible easily to provide for heating or cooling of the extracorporealblood, its oxygenation or degasification under reduced or augmentedpressures, the addition of drugs or other materials, or for othervariations on the simple oxygenation of the blood.

The preferred form of apparatus of this invention is a sphere with ablood reservoir at the bottom, resembling an inverted Florence flask.While its theory forms no part of this invention, it is considered thatthe stretching and contracting of the film first as it approaches thehorizontal diameter, and then as it approaches the reservoir causes agentle but elfective tumbling or turbulence of the blood and its redcells, which makes the apparatus particularly effective. As has beenindicated in the objects, a result of this effectiveness, both in theoxygenation, and in the non-frothing aspect, is that the apparatus canbe made relatively small, and the reservoir of blood can be small, sothat little priming is necessary, and, even with recirculation, the lossof the blood to the subject during the bloods extracorporealcirculation, is not untoward.

In the drawing, FIGURE 1 is a sectional view along the longitudinal axisof one embodiment of aerating container of this invention; with certainappurtenances shown somewhat diagrammatically;

FIGURE 2 is a diagrammatic view of one embodiment of apparatus of thisinvention; and

FIGURE 3 is a diagrammatic view of another embodiment of apparatus ofthis invention.

Referring now to the drawing for an illustrative embodiment of apparatusof this invention, reference numeral 1 indicates an oxygenatingcontainer, spherical except for a cylindrical reservoir 2 at its lowerend.

A venous blood conduit 3 extends through the reservoir 2, anddiametrically into, and through substantially the full height of thecontainer 1, terminating with an outlet 4 positioned adjacent theunderside of the uppermost point of the dome of the container, infilming relation thereto. A conical drip shield 6 is secured to andaround the outside of and near the upper end of the conduit 3.

Concentric with and spaced radially outwardly from the venous bloodconduit 3 is a gas outlet tube 10, open at its upper end to form aninlet 11, and sealed at its lower end, below the blood reservoir 2,around the venous blood conduit. Near its lower end, below the reservoir2, the tube 10 communicates with a waste gas outlet tube, which may bevented to the atmosphere, or, if super or sub-atmospheric pressure isindicated in the container 1, to a pressure valve or vacuum source, asthe case requires. In the embodiment illustrated, it is vented to theatmosphere.

In the embodiment shown, the inlet 11 of the tube 10 is positioned nearthe horizontal diametric plane of the container 1. As is clearly shownin FIGURE 1, the tube 10 is sufficiently spaced from the conduit 3 toleave a clear passageway 12 between them.

An oxygen admitting tube 20 surrounds and is concentric with the gasoutlet tube 10, and is spaced radially from it to provide a passage 21between them. The oxygen admitting tube 20 ends, at its upper end, withan open outlet 22, positioned substantially below the waste gas inlet11. At its lower end, below the reservoir 2, the oxygen tube 20 issealed to and around the Waste gas outlet tube 10, and, below thereservoir 2, it communicates with an oxygen pipe 24, which, in turn,communicates with a source of oxygen-rich gas 26. An oxygen-rich gasdeflection shield 25 is secured to and around the tube 10 above the openoutlet 22 at a distance such as not to impede the flow of gas from theoutlet 22 but to tend to deflect its course radially outwardly.

An arterialized blood conduit 30, which communicates with the bottom ofthe reservoir 2, completes the fittings of the oxygenating container. I7

Outside of the container 1 and its fittings, the system of thisinvention includes a venous blood supply line 40, an arterial bloodreturn line 50 connected to the arterialized blood conduit 30, a shuntline 54, with a valve 55 in it and a blood pump 45, which may be astandard DeBakey roller pump, connected in the venous blood line 40, topump blood from a subject 100 and into the venous blood conduit 3, andalso connected in the return line 50, to pump arterial blood from thereservoir 2 and into the subject 100. The valve 55 may be a simple cockor clamp, or it may be a check valve permitting flow only toward thevenous supply line 40, or it may I be an adjustable pressure-responsivevalve, and is preferably the latter. A flow meter 56 is also in line 54.i

The venous blood supply line 40 is connected, inuse, to a vein of thesubject the arterial blood return line 50, to an artery. The operationof the simple device illustrated in FIG- URE 2, will be illustrated interms of actual laboratory use with dogs. This is, of course, merely byway of illustration, and is not to be considered limitative.

For a 20 kilogram female dog, upon which an operation was to beperformed, a 12 inch diameter globe was used, primed with 500milliliters of saline solution. The venous blood conduit 3 had aninternal diameter of approximately inch, and was cut off squarely. Theoutlet 4 was positioned approximately inch from the inside surface ofthe axial center of the dome.

The venous blood line 40 was connected to the superior and inferiorvenae cavae of the animal and the arterial blood return line 50 wasconnected to the animals left femoral artery. The valves 41 and 51 wereclosed and the valve 55 opened. The pump 45 was started and regulated todeliver 4 liters per minute of flow as indicated by the flowmeter 56.The saline solution was circulated through the shunt line 54, venousblood line 40, venous blood conduit 3, arterialized blood conduit 30 andarterial blood return line 50, filming on the inside surface of thedome, wetting the container wall and preparing the system for thereception of the animals blood. The sweep of oxygen-rich gas through thecontainer was then begun. In this instance, pure oxygen was supplied tothe interior of the globe at the rate of 4 liters per minute, andexhaust gases were vented to the atmosphere. The pressure in theinterior of the container 1 was less than 14 pounds p.s.i.g. The valves41 and 51 were then opened and the shunt valve 55 adjusted so as tosupply blood or, initially, a mixture of blood and saline solution, tothe animal, and to remove blood from the animal at the rate of about 1liter per minute. In this way, in a relatively short time after theextracorporeal circulation was begun, most of the blood was recirculatedthrough the oxygenating container about three times before its return tothe animal.

In a series of tests, the simple apparatus shown and described has beenused for periods of total cardiopulmonary by-pass during operations ondogs, varying in length from 5 to 70 minutes, with no operativemortality attributable to the design and function of the apparatus.

It can be seen that with different animals, including human beings, itmay be necessary or desirable to change the rate of flow of gas or bloodor both, the size of the container, and the composition, volume andperhaps pressure of the oxygen-rich gas. These changes, in turn, mayrequire different dimensions of the various tubes and conduits, butthese are mechanical adjustments which will be readily understood bythose skilled in the art.

In FIGURE 3, a system is shown, in highly diagrammatic form, whichincorporates several attachments to or variations in the simple systemshown in FIGURE 2. In the venous blood supply line 40, between the shuntline 54 and the pump 45 there is shown a reservoir 70, connected withthe venous blood line 40 by a line 71 in which is a valve 72. Thereservoir 70 has been used as a coronary sinus reservoir for coronaryblood collected by suction. Drugs, saline solution, nutrients, or thelike, can also be introduced to the blood stream from the reservoir 70.Several such reservoirs or their equivalents can be provided, ifdesired.

In FIGURE 3, the oxygenating container 1 is shown as being used as aheat-exchanger also. This has been found to be an excellent arrangement.The container may be provided with a jacket 80, as shown, with thermalfluid inlet and outlet pipes 84 and 85, connected to suitable sources ofwarm or cold fluid and drain or return lines, respectively.Alternatively, thermal fluid, e.g. warm or cold water, may simply beflowed over the outer surface of the container, or coils can be providedaround it, or it can be positioned in an open bath. Since the blood isfilmed, the heat transfer between the thermal fluid and blood has beenfound to be quite efficient. It may be found desirable, from the gasexchange point of view, or to minimize damage to the blood, to both cooland heat the blood, at different stages. To these ends, a

4 separate heat exchanger may be provided in the line 40 or 50 or both.

A pressure equalization tank is also shown. The tank 90 can be usedeither in conjunction with the heating and cooling system, or, if theblood is aerated at super or sub-atmospheric pressures, it can serve asa safety device to ensure that the blood immediately before it is pumpedback to the body is at atmospheric pressure. Super-atmospheric pressurecan be had by putting a valve on the excess gas outlet and thusrestricting the escape of gas, permitting the pressure to build uptoward the pressure of the source of oxygen-rich gas. Sub-atmosphericpressure can be had by attaching a vacuum pump to the excess gas outlet,and putting a restricting valve in the oxygen rich gas inlet 24. Theblood is preferably pumped out, into a tank such as tank 90, by a pumpsynchronized with the pump 45, or by the pump 45 itself, if the tubingcan be so arranged.

The provision of the shunt line and valving providing a variableresistance to flow through the shunt, has been found to be a greatimportance. With a pressure differential type valve in the shunt line,responsive to either a build-up of pressure in the arterial blood returnline 50 or a drop in pressure in the venous blood supply line 40, thereis partically no danger of producing a dangerously high pressure on thearterial side or dangerously low pressure on the venous side. Thepressure on the venous side is normally practically atmospheric.

The flowmeter 56 is preferably provided with one inverted scale. Bypositioning the flowmeter in the shunt line, the operation of the pump45 can be checked at the onset, and the rate of flow regulated. The pumpcan then be left at one setting, since it receives and delivers exactlythe same amount of liquid, and the perfusion rate is governed by varyingthe resistance in the shunt line. While it is conceivable that the shuntline might be blocked, this is highly improbable, because there isalways a substantial flow through it. For safety, an attachment to thedifferential valve can be used to shut off the pump 45, but, unlike mostpresent commercial aerators, a temporary blockage will not shut down theentire machine. The presence of a blockage in the subject on either thevenous or arterial side will be signaled immediately by the flowmeter,because the flow through the shunt line will increase.

This will appear as a decrease on the inverted scale, which will readthe difference between the total flow and the flow through the shuntline, which must be the perfusion rate.

For some reason, believed to be related to the substantial absence ofpriming blood and to the gentleness of the system, it has been foundthat pure oxygen can be used satisfactorily as the oxygen-rich gas inthe operation of the system with laboratory dogs. However, the usualoxygen-carbon dioxide mixture may be found desirable in othercircumstances, or different mixtures of gases, but they do not form apart of this invention.

Numerous variations in the construction and operation of the apparatusand method of this invention respectively, within the scope of theappended claims, will occur to those skilled in the art in the light ofthe foregoing disclosure. For example, the container is preferably madeof glass or transparent or translucent plastic, so that the filming andoxygenating of the blood can be checked visually, but other materialsmay be used. Similarly, the piping can be made of various differentmaterials. Different forms of pumps are operative. Valves of varioussorts may be employed in the system. While the spherical type domedcontainer is preferred, an inverted pear-shaped, ovoid, acorn-shaped oreven conedomed container may be used, if the blood can be filmed gentlyfrom a central point, substantially circularly. The volume ofrecirculating blood can be altered both in absolute amounts and relativeto the circulation of fresh blood, and various amounts and mixtures ofoxygenrich gases can be used. These are merely illustrative.

Of course, a plurality of oxygenating containers may be employed, inseries or parallel, but the greatly increased surface area obtained withan increase in diameter of a spherical container makes it possible toaccommodate and oxygenate a large volume of blood with relatively littleincrease in size of a single oxygenating container, so that a pluralityof containers need not ordinarily be employed.

Having thus described the invention, what is claimed and desired to besecured by Letters Patent is:

1. Apparatus for oxygenation of blood, comprising a stationary, lightpermeable container having a dome; venous blood conduit means extendingwithin, and directed upwardly toward the upper inner surface of the domeof said container, and outlet for said conduit opening upwardly at theupper inner surface of the dome of said container and spaced therefroman amount whereby a flowing stream containing blood at dischargevelocity from said outlet can produce a gentle filming on the innersurface of said dome from a central point of the stream substantiallycircularly over the inner dome surface; an arterialized blood conduitmeans communicating with a part of said container lower than said dome,in which blood accumulates; an oxygen admit-ting tube above said part ofthe container and below the venous blood conduit outlet; a gas outlet,and pump means for forcing blood through said venous blood conduit meansand for removing an equal volume of arterialized blood from saidcontainer through said arterialized blood conduit means.

2. The apparatus of claim 1, wherein shunt means are provided,interconnecting the venous blood conduit means and the arterializedblood conduit means, whereby arterialized blood is recirculated throughsaid venous blood conduit means, and metering means operativelyconnected to said shunt means for regulating the perfusion rate of theapparatus while maintaining the pump output constant.

3. The apparatus of claim 1 wherein thermal liquid means are providedfor bathing at least a portion of the exterior surface of theblood-filming wall of the container in thermal liquid at a controlledtemperature diflerent from the ambient temperature of the space in whichthe apparatus is.

4. The combination as defined in claim 1 in which said pump means haveequal flow rates and a shunt line having a variable restriction connectsthe output side of one of said pump means with the input side of theother pump means, whereby the volume of liquid withdrawn from, andintroduced into the subject remains constant for a given setting of saidrestriction.

5. Apparatus for oxygenating fluent blood comprising a hemisphericallydomed light permeable container, the dome being uppermost, and, in orderof height of opening and radial distance from the center, a venous bloodconduit means extending within, and directed upwardly toward the upperinner surface of the dome of said container, an outlet for said conduitopening upwardly at the upper inner surface of the dome of saidcontainer and spaced therefrom an amount whereby a flowing streamcontaining blood at discharge velocity from said outlet can produce agentle filming on the inner surface of said dome from a central point ofthe stream substantially circularly over the inner dome surface, a gasventing tube concentrically arranged about said venous blood conduit andhaving an outlet concentric with the opening of the venous bloodconduit, and an oxygen admitting tube concentrically arranged about saidgas venting tube, and having an outlet concentric with the gas ventingtube outlet, the outlets of the gas venting and oxygen admitting tubesbeing oflset vertically from one another and from the venous bloodconduit opening, with the gas venting tube outlet intermediate the othertwo.

6. Apparatus for oxygenation of blood, comprising an oxygenatingcontainer having a dome, venous blood conduit means leading to andextending within said container, said venous blood conduit meansincluding a tube extending within and directed upwardly toward the uppersurface of the dome of said container and provided with an outletopening upwardly at the upper inner surface of the dome of saidcontainer, spaced therefrom an amount whereby a flowing streamcontaining blood at discharge velocity from said outlet can produce agentle filming on the inner surface of said dome, from a central pointof the stream substantially circularly over the inner dome surface,arterialized blood conduit means leading from said container, pump meansin the venous blood and arterialized blood conduit means arranged topump an equal flow rate of liquid through both said conduit means, ashunt line connected between the venous blood conduit and arterializedblood conduit means on the suction side of the pump means in the venousblood conduit means and the discharge side of the pump means in thearterialized blood conduit means whereby the blood is recirculatedwithout build up of pressure in said arterialized blood conduit means,and variable resistance means in the shunt line, whereby with a constantoutput of said pump means, a variable flow of blood through the shuntline can be effected.

References Cited in the file of this patent UNITED STATES PATENTS2,659,368 Gibbon et al Nov. 17, 1953 2,760,922 Williams Aug. 28, 19562,827,901 Jones Mar. 25, 1958 2,896,620 Tremblay July 28, 1959 2,927,582Berkman et al. Mar. 8, 1960 3,017,885 Robicsek Ian. 23, 1962 OTHERREFERENCES Dickson et al.: A System for Ven-Arterial Pumping, Surgery,vol. 45, No. 2, February 1959, pages 288-291.

1. APPARATUS FOR OXYGENATION OF BLOOD, COMPRISING A STATIONARY, LIGHTPERMEABLE CONTAINER HAVING A DOME; VENOUS BLOOD CONDUIT MEANS EXTENDINGWITHIN, AND DIRECTED UPWARDLY TOWARD THE UPPER INNER SURFACE OF THE DOMEOF SAID CONTAINER, AND OUTLET FOR SAID CONDUIT OPENING UPWARDLY AT THEUPPER INNER SURFACE OF THE DOME OF SAID CONTAINER AND SPACED THEREFROMAN AMOUNT WHEREBY A FLOWING STREAM CONTAINING BLOOD AT DISCHARGEVELOCITY FROM SAID OUTLET CAN PRODUCE A GENTLE FILMING ON THE INNERSURFACE OF SAID DOME FROM A CENTRAL POINT OF THE STREAM SUBSTANTIALLYCIRCULARLY OVER THE INNER DOME SURFACE; AN ARTERIALIZED BLOOD CONDUITMEANS COMMUNICATING WITH A PART OF SAID CONTAINER LOWER THAN SAID DOME,IN WHICH BLOOD ACCUMULATE; AN OXYGEN ADMITTING THE TUBE ABOVE SAID PARTOF THE CONTAINER AND BELOW THE VENOUS BLOOD CONDUIT OUTLET; A GASOUTLET, AND PUMP MEANS FOR FORCING BLOOD THROUGH SAID VENOUS BLOODCONDUIT MEANS AND FOR REMOVING AN EQUAL VOLUME OF ARTERIALIZED BLOODFROM SAID CONTAINER THROUGH SAID ARTERIALIZED BLOOD CONDUIT MEANS.